For a 0.1M solution Dissolve 29 g of zinc sulphate in sufficient water to produce 1000 ml.
To 20 ml add 5 ml of 2M acetic acid in a 500 ml conical flask dilute the prescribed solution to 200 ml with water and add about 50 mg of xylenol orange triturate and sufficient hexamine to produce a violet-pink colour. Add a further 2 g of hexamine and titrate with 0.1M disodium edetate VS until the colour changes to yellow. Each ml of 0.1M disodium edetate VS is equivalent to 6.54 mg of Zn.
1) Discard the solution after 30 days.
2) Restandardise before use
3) For storage and labeling follow the general procedure.